A previous method for recovering rhenium from material containing tungsten and rhenium such as scrap wire involves heating the scrap in air to a temperature at which both tungsten and rhenium are oxidized. Rhenium heptoxide, being volatile, sublimes from the tungsten oxide and is collected in a cooler portion of the furnace system. The rhenium is then removed by dissolution in water to form soluble perrhenic acid which can be processed chemically to other desired rhenium compounds.
A disadvantage of this method is a low recovery efficiency of contained rhenium. Substantial amounts of rhenium remain with the tungsten. Another disadvantage is the need for a capital investment in a furnace to carry out the oxidizing, subliming, and condensing steps.